sid Wrote: ------------------------------------------------------- > > So I guess (without trying) you can fuse more cans > to one bigger plate, > but how would that lead to new filament? Sid, If one could make a void-free plate (imagine it's a disk, for now, ~3 mm thick), then one could slit that, in a spiral fashion, into a long spiral of void-free plastic. The cross section ofby Larry_Pfeffer - Plastic Extruder Working Group
Greetings all, I know little about thermoplastic processing, and I'm curious about what materials, finishes (and mold release compounds?) are used to let the molded part come out of the mold, without such a fight that the parts or mold are damaged. Are the molds "simply" highly polished metal? or do they have some special coating that thermoplastics don't stick to very well. Similarly, if oneby Larry_Pfeffer - Plastic Extruder Working Group
Bob, That mtg. was *last* summer. Sorry to dissapoint you (but wouldn't want you to drive up for no reason.) I sent you an invitation to join the google group that's more active: If you have any problems or questions, please email me. -- Larry ursine @t gm4il d0t c0mby Larry_Pfeffer - Rhode Island / New England RUG
Greetings Dave, We've mostly migrated to a google group: Take a look, and if you're interested, let me know your email address and I'll add you as a member. You can email me at ursine @t gmail d0t c0m Best Regards,by Larry_Pfeffer - Rhode Island / New England RUG
Greetings all, Another option for USB-to-Sanguino connection is the "USB BUB" kit from This comes with the surface-mount chip already soldered to a PC board, and it's cheaper than the FTDI cable ($12.90 {USD} vs ~$20.) I've had good luck with this Co. and products.by Larry_Pfeffer - Controllers
Enleth, Nice work! Once this extruder has been used, can you unscrew the copper nozzle easily, or is it hard to unscrew? You might consider putting wrench flats on the copper nozzle, so users can apply more torque, without deforming it with pliers, etc. (And brass is stronger than copper, which is why I used it for my screw-in nozzles.) HTH,by Larry_Pfeffer - For Sale
Hazel, ESR stands for "Effective Series Resistance." All real capacitors cannot charge (or discharge) infinitely fast. For now, let's leave superconductivity, inductance and distributed-parameter effects out of the discussion. Any real circuit with a capacitor contains at least a little resistance, from the capacitor's leads and the capacitor plates (as well as some related delays from thby Larry_Pfeffer - Controllers
Hazel, If you want to stick with a surface mount part, you'll need to make sure the contact dimensions are the same as the original part (and that the overall part size is either the same, smaller, or not enough larger to encroach on neighboring parts. TI found the dimensions for the D55 package can be found at: (FYI, I searched for: SMT pad dimensions "D55" ) The other specs to check:by Larry_Pfeffer - Controllers
Philwaud2 Wrote: ------------------------------------------------------- > I don't know if it helps but I plugged an old hard > drive in, all works fine then! That sounds like your power supply needs a minimum load on it. The disk will do, for now. But you might want to find a cheaper load resistor, esp. if you have data on the disk, or other use for it. (One low-cost/easy-to-get loadby Larry_Pfeffer - Controllers
Damon, Where did you get your tungsten electrodes, and how much did they cost? I might try something similar, using higher voltage capacitors (e.g. from disposable cameras.) Higher voltage (through the same resistance) should lead to higher instantaneous power -- unless inductive effects dominate resistive ones. Thanks, Larryby Larry_Pfeffer - Plastic Extruder Working Group
Interesting, -- And not anything like what I had imagined for thermocouple welding. I thought that one sent the Cap. discharge down the thermocouple wires themselves, and that, where the bare metals touched, there was a higher resistance, so there would be more power locallized there during the discharge. I didn't think one used separate electrodes, with the thermocouple junction between. Iby Larry_Pfeffer - Plastic Extruder Working Group
damonb Wrote: ------------------------------------------------------- > I also obtained some 34 gauge J type thermocouple > wire from Electronics Goldmine. I used capacitive > discharge welding to weld the wires together. Damon, I'd be very interested in hearing about what capacitors, etc. you used to do the discharge welding. Perhaps something adapted from a camera-flash circuit?by Larry_Pfeffer - Plastic Extruder Working Group
Greetings Damon, et al, I have used the flexiforce sensors (and also similar sensors made by interlink, ) They both have a non-linear response (resistance roughly inversely related to applied force), and some hysteresis effects, but they produce a huge signal, compared to strain gages. The most common of these are disk shaped, although interlink makes (or at least made, not sure now) square pby Larry_Pfeffer - Plastic Extruder Working Group
labmat, Good to hear you have the hardware and software needed to use the original motion controller. Having extra channels gives you the possibility to build servo-driven extruders! BTW, I keep one of my older PCs around because it has a few ISA slots, and I have a couple ISA cards useful for motion control. Keep us posted on your progress. It looks like you have the foudation for an excellby Larry_Pfeffer - Controllers
labmat, I took a quick look at that datasheet, and I have two questions you probably want to think about: Do you have the *software* for programing this board? Also, it's an ISA card (several generations back in PC add-on slot interfaces.) So, do you have a (working) PC with an ISA slot to put the MEI board into?by Larry_Pfeffer - Controllers
Greetings all, I agree that pre-computing the bit patterns is a good idea, esp. for use in an ISR. However, if they are pre-computable, you'd do much better to make them const (const enums is fine) or #defines. Then the compiler can use the fastest (of many) ways to get that bit pattern into a register in the ISR. Declaring these patterns to be global volatile *forces* the compiler to (re-)by Larry_Pfeffer - RepRap Host
Greetings all, I agree that pre-computing the bit patterns is a good idea, esp. for use in an ISR. However, if they are pre-computable, you'd do much better to make them const (const enums is fine) or #defines. Then the compiler can use the fastest (of many) ways to get that bit pattern into a register in the ISR. Declaring these patterns to be global volatile *forces* the compiler to (re-)by Larry_Pfeffer - RepRap Host
Thanks for the sketch; *now* I see what you'r thinking of! OK, that mechanism does what you said. However, it needs two sliding bearings (that can share the same "track") plus eight rotary bearings (that had better not have off-axis play.) I'm not sure whether that's really easier than a pair of linear bearings, though the notion of sharing one motor between two degrees of freedom is certainlby Larry_Pfeffer - Mechanics
SOI Sentinel Wrote: > I also have another idea that may be interesting. > It's a partial delta robot. Take the bed and put > two screws on it. Put each side on a > parallelogram hinge facing opposite ways. Drive > the two screws in the same direction and you get > bed lateral motion. Drive the screws in opposite > directions, and you get bed vertical motion. With >by Larry_Pfeffer - Mechanics
Labmat, That, my friend, is a real find! Are there any more available?!? FYI, reprap core member Nophead based his machine, on a somewhat similar XY stage. I heartily suggest you read his blog, especially (in your case) the early posts, where he documents his Cartesian mechanism.by Larry_Pfeffer - Controllers
Jeremy, From your last message, I'll assume you're in the (continental) US. I urge you to take a look at used machines and/or get ahold of some instructional material on the basics of machining before you finalize your purchase selection(s.) If you're within an hour's drive of a good-sized city, watch eBay and/or the local craigslist site for machines even remotely like what you want. You mby Larry_Pfeffer - CNC Routers, Mills, and Hybrid RepRapping
Greetings all, I'm finally on the scoreboard in the Cortex game, albeit just barely. I had been unable to get my little STM32 Cortex board to talk at all (wasn't being recognized by the STM flash loader utility.) I found my error (a loose solder joint on a voltage regulator), and now it talks. To set up the toolchain and program a blinking LED, I adapted the instructions from More detby Larry_Pfeffer - RepRap Host
Jeremy, For what it's worth, I second the above advice that combo tools can be a real pain! If you only have space for one, the conventional wisdom seems to be to get a lathe and a milling attachment for it. It's not a great milling setup, but it's better than trying to do lathe work on a mill. And if you get a combo machine, I suggest trying hard to get one with separate motors. (Easier toby Larry_Pfeffer - CNC Routers, Mills, and Hybrid RepRapping
Hazel, et al, The Gen-3 motherboard does indeed have a Sanguino-equivalent (in surface-mount) on it. The motherboard also has two rows of through holes (on tenth inch spacing) so that you could solder in some in-line connector strips and plug in a through-hole Sanguino in lieu of the surface-mount parts. HTH,by Larry_Pfeffer - Controllers
annodomini2 Wrote: > Does the cortex have an FPU? Not really had much > exposure to ARM chips The Cortex M3 (and M0) do not have an FPU. (Not sure about the other variants, like the A-series, as used in the beagle board.) The full ARM architecture (most modern versions, such as the ARM9) define a co-processor interface, and they can use that to communicate with a conceptually-separatby Larry_Pfeffer - Controllers
Greetings all, annodomini2 Wrote: > Almost there, most processors have 2 types of > register Value and Address. The Cortex architecture doesn't have this (IMHO, unhelpful) separation. Cortex registers can hold either a pointer or a value. So, one can load the contents of a pointer (in a register) into that same register. (This assumes that the contents will fit; if the contents areby Larry_Pfeffer - Controllers
Hazel, et al, One of the main points of a PC board (at least a properly-done one) is that there is printing on the board "art layer" showing what components go where, and their orientation. So, you don't need to understand the circuit to stuff and solder it. The Sanguino board is labelled this way. Of course, to fix problems if they occur, some understanding (and a meter, etc.) is helpful, bby Larry_Pfeffer - Controllers
MotorAssist Wrote: ------------------------------------------------------- > I have just seen the post on the Paperduino, and > after looking at the website thought that may be > something I can do. After all, I can follow > instructions! Hello Hazel & Co., Except for getting away from the cost of a PC board, I don't see the Paperduino as being easier for a newbie to get workby Larry_Pfeffer - Controllers
Greetings all, I agree that K&R is a great book; get the 2nd edition, unless there's an even later one now. I have several C texts, but that's the one that's right where I can get it. I even had my falling-apart copy rebound (rather than buy another) because the old one has all my margin notes and post-its marking places I continually refer to. (e.g. the page describing printf specifierby Larry_Pfeffer - Controllers
Graham, Congrats on your progress with your STM32 Cortex board! (I agree with you, as chip packages proliferate {and get smaller}, it's harder to be sure about where pin 1 is. Oh, for the good old unambiguous DIP packages....) I haven't done much yet with my STM32 modules, mostly reading about the CPU, and building a USB -> serial rig for my laptop. Buying one would have been more time eby Larry_Pfeffer - Controllers